This invention relates to the field of permanent press compounds. Specifically this invention relates to a series of materials which are reactive with cellulose type hydroxyl groups to impart crosslinking and, therefore, permanent press properties to cellulose and cellulose blend fabrics. Such compounds have crosslinking properties similar to the more familiar formaldehyde derived adducts, currently used in permanent press application, without the use of any undesirable formaldehyde.
Treatments for fabrics composed of cellulose and mixtures of cellulose with natural or synthetic polymers to render them wrinkle resistant and self-smoothing on laundering, consist of applying and reacting a finishing agent on the cellulose. These finishing agents form crosslinks or bonds between linear cellulose molecules of which the fiber is composed and are typically made from a reaction of formaldehyde with ureas to make a polyfunctional methylolamide or hydroxymethylolamide. These methylolamides are applied from aqueous solution and, after drying, react readily with cellulose under the influence of mild catalysts. Because they have more than one reactive methylolamide group, they form bridges or crosslinks between the linear cellulose molecules, thereby imparting permanent press properties to the fabric.
While these crosslinking treatments do increase the wrinkle resistance and durable press properties of the cellulosic fabric, they also decrease the ability of the fiber to absorb moisture. This is shown by the reduced moisture content of the fabric when exposed to atmospheric moisture. Additionally, the presence of formaldehyde in the adducts renders the agents as less desirable for many applications, since formaldehyde has been linked with many health problems.
To avoid these drawbacks, researchers have tried a wide array of materials as crosslinking agents. For example, Frick, Jr. et al. (U.S. Pat. No. 4,619,668), disclose a variety of materials, produced by reaction of 1,3-dimethylurea and glyoxal, which are useful as permanent press agents. The patentees therein state that the resultant compositions produce a satisfactory degree of crosslinking, while imparting a high degree of wettability to the fabric; this wettability is important in dyeing operations, since most dyes are applied from aqueous solutions.
The use of similar compounds, including substituted imidazolidinones, is also known in the art. However, many of such materials also possess a drawback of imparting a yellow tint to the fabrics when chlorine bleach is applied, due to the presence of free amine hydrogens. Therefore the use of such materials in permanent press fabrics for wearing apparel is extremely limited.
There exists a real need for compounds which are suitable for use as cellulose crosslinking agents, which overcome the drawbacks with the prior crosslinking agents. Such compounds will impart a high degree of permanent press and smoothablity to the fabrics, yet avoid the use of toxic formaldehyde, and additionally, be obtainable in high yields, relatively stable to storage, and useful in many different applications.